1. Field of the Invention
The present invention relates to hydraulic couplings used in undersea drilling and production applications and seals used in those couplings. More particularly, the invention involves a seal retainer that restrains one or more radial seals from imploding into the bore of the female member when the coupling is disassembled.
2. Description of Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male and a female member with soft seals positioned within the female member to seal the junction between the male and female members. The female member is generally a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains soft seals and receives the male portion of the coupling. The male member includes a cylindrical portion or probe at one end having a diameter approximately equal to the diameter of the large bore in the female portion of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to the various embodiments of the device, the soft seals, resembling O-rings, either abut the end or face of the male member or engage the cylindrical probe wall about its circumference. The hydraulic fluid is then free to flow through the female and male portions of the coupling, and the seals prevent that flow from escaping about the joint and the coupling.
In some instances, a check valve may be installed in the female member and also in the male member. Each check valve opens when the coupling is made up and closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is a part.
In U.S. Pat. No. 4,694,859 to Robert E. Smith, III, assigned to National Coupling Co., Inc., an undersea hydraulic coupling and metal seal is disclosed. This patent discloses a coupling with a reusable seal which engages the circumference of the probe and is positioned within the female member body. The metal seal is held in place by a cylindrical body or retainer. When the male and female portions of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member. U.S. Pat. No. 4,694,859 also discloses a soft annular seal or O-ring at the inner cylindrical surface of the retainer, which engages the probe circumference. The soft annular seal generally is used as a secondary seal, and prevents escape of hydraulic fluid should the metal seal fail. As the probe begins to the enter the retainer bore, it begins to engage the soft annular seal intermediate the retainer bore. This contact compresses the seal and creates a sliding seal between it and the probe wall. The annular seal or soft seal is of relatively pliable material, for example, rubber or synthetic elastomere. The annular seal is generally ring shaped in and is located in a groove in the bore.
If the male member or probe is removed from the female member under high ambient seawater pressure, the soft annular seal oftentimes will blow out of the female member bore and be lost. The implosion of the soft seal is a characteristic problem in the prior art. As the male member or probe is pulled out of the female member bore, and the leading face of the male member reaches the midpoint of the soft annular seal, there is nothing to restrain the seal from radial movement into the bore. Very low pressure or vacuum in the bore may result in the seal being imploded into the bore, as the ambient seawater begins to enter the bore at high pressure. If the soft annular seal blows out through the female bore, it may be extremely difficult to replace the seal within the bore. There are also difficulties encountered in machining a groove in the female bore for the seal and inserting the seal in that groove.
Several undersea hydraulic couplings have been designed to restrain the seal from radial movement into the bore. For example, U.S. Pat. Nos. 4,900,071 and 5,052,439 to Robert E. Smith, III, assigned to National Coupling Co., Inc., disclose undersea hydraulic couplings with dovetail seals. The dovetail seals are restrained from radial movement by a dovetail interfit with a mating shoulder on the retainer sleeve and/or the retainer locking member. The inner cylindrical surface of the dovetail seal engages the circumference of the male member or probe as the probe is inserted through the retainer into the female member. The coupling also may have a reusable metal seal that is held on a shoulder in the female bore by the retainer. The metal seal is pressure energized so that hydraulic fluid pressure acting on the seal tends to urge the seal radially inwardly against the probe and radially outwardly against the female member body.
The dovetail seals in U.S. Pat. Nos. 4,900,071 and 5,052,439 are not pressure energized. In some applications, it is desirable to use a pressure energized seal as the secondary seal, instead of the dovetail seal. This is desirable because at greater ocean depths, the need to prevent leakage of hydraulic fluid from the coupling is critical. Additionally, due to increased subsea pressures at greater ocean depths, there also is a critical need to prevent implosion of seals into the coupling bore when the male member and female member are separated.
The present invention overcomes the above mentioned problems and disadvantages by providing an undersea hydraulic coupling having a seal retainer that holds a pair of pressure energized seals in the female member bore, and restrains at least one of the seals from radial movement or implosion into the bore when the coupling members are separated. The retainer holds a first pressure energized radial seal on a shoulder in the female member bore and, additionally, has a projection extending longitudinally therefrom to hold a second pressure energized radial seal and restrain the second seal from radial movement into the female member bore. The second seal preferably is an elastomeric seal. The projection extending from the seal retainer extends into the hollow portion of the second seal.